PAHs 對口腔與支氣管上皮細胞的毒性作用

The cytotoxic effect of polycyclic aromatic hydrocarbons in oral and bronchial epithelial cells

許瑭裕(Tan-Yu Hsu)

指導教授 ： 林常申

高雄醫學大學/醫學院/醫學研究所/碩士(2008年)

摘要

摘 要
多環芳香族碳氫化合物 (polycyclic aromatic hydrocarbons，PAHs)， 主要由兩個或以上芳香環組成的一大群有機異構物，大約超過一千多種。透過吸菸與各種有機化合物的不完全燃燒過程中產生，對人類具有很高的致癌性。這些化合物在生物體內經代謝後產生的代謝衍生物有些會與DNA形成DNA adducts，造成DNA受損。為了了解PAHs在香煙致癌過程中扮演著和種重要角色，我們使用了不同的PAHs處理口腔 (KB) 與支氣管上皮細胞株 (Beas-2B)，觀察PAHs對兩株細胞株的基因毒性與細胞毒性影響。實驗中使用根據美國環境保護協會發佈優先評估的九種PAHs，作為主要研究對象。首先以PAHs處理細胞24小時後，以MTT assay觀察細胞存活率表現，結果發現BaA、BaP、FL處理的Beas-2B，其MTT吸光值有增加，但對KB並未有太大影響。兩株細胞經PAHs處理7天或更長的時間後，其MTT吸光值則下降。在細胞週期的分析中，發現KB經由BaP處理24小時後，S phase的細胞比例增加，但Beas-2B並沒有太大影響。當Beas-2B經BaP處理7天後，停滯在G2/M phase的細胞比例增加。為了了解BaP對細胞的毒性作用使否與其造成的DNA受損或干擾DNA修復有關，我們以轉染方式送入經紫外光處理的報告質體進行宿主細胞質體再活化試驗，觀察PAHs是否會干擾宿主進行DNA的修復。結果發現BaP確實會干擾兩株細胞的核苷酸切除修復 (nucleotide excision repair，NER) 修復系統，使DNA的修復效率降低。此外，我們也發現兩株細胞經過BaP處理後，微核的形成逐漸增加。故推側BaP可能藉由抑制DNA損傷的修復，使細胞的DNA損傷逐步累積，造成基因體的不穩定。

關鍵字

多環芳香族碳氫化合物

並列摘要

Abstract
Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds composing of two or more fused aromatic rings. Probably have more than 1000 kinds. They are produced by cigarette smoking and by any type of incomplete combustion. PAHs may be carcinogenic to human. Their metabolites may form adducts with DNA and may induce DNA damage. To examine the roles of PAHs in contributing cigarette smoking-associated human malignancies, we investigate cytotoxicity and genotoxicity of various PAHs in oral (KB) and bronchial epithelial (Beas-2B) cell lines. The 9 PAHs with potential carcinogenicity announced by the United State Environmental Protection Agency were used in this study. By MTT assays done after PAHs treatment for 24 hr, we found that BaA, BaP, and FL-treated cells exhibited growth advantage in Beas-2B but not in KB cells. However, the cell growth was repressed in both cell lines when they were incubated with PAHs for one week or longer periods. Flow cytometric analyses showed that BaP treatment for 24 hr could increase S phase propotion in KB but not in Beas-2B cells. When Beas-2B cells were incubated with BaP for 7 days, most cells were arrested in G2/M phase. To examine whether the cytotoxicity of BaP was correlated to BaP-associated DNA damage and repair, we conducted host cell reactivation assays, which could evaluate nucleotide excision repair (NER). The results showed that BaP could inhibit NER both in KB and in Beas-2B cells. Besides, we found that micronucleus formation was increased in BaP-treated KB and Beas-2B cells. These results suggested that BaP could repress DNA repair and induce sign of genomic instability.

並列關鍵字

NER

參考文獻

參 考 文 獻

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